scholarly journals Improving Fatigue Limit and Rendering Defects Harmless through Laser Peening in Additive-Manufactured Maraging Steel

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 49
Author(s):  
Shiori Tsuchiya ◽  
Koji Takahashi
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
Maraging Steel ◽  
Compressive Residual Stress ◽  
Surface Defects ◽  
Defect Size ◽  
Specimen Surface ◽  
Dominant Factor ◽  
Laser Peening

Additive-manufactured metals have a low fatigue limit due to the defects formed during the manufacturing process. Surface defects, in particular, considerably degrade the fatigue limit. In order to expand the application range of additive-manufactured metals, it is necessary to improve the fatigue limit and render the surface defects harmless. This study aims to investigate the effect of laser peening (LP) on the fatigue strength of additive-manufactured maraging steel with crack-like surface defects. Semicircular surface slits with depths of 0.2 and 0.6 mm are introduced on the specimen surface, and plane bending-fatigue tests are performed. On LP application, compressive residual stress is introduced from the specimen surface to a depth of 0.7 mm and the fatigue limit increases by 114%. In a specimen with a 0.2 mm deep slit, LP results in a high-fatigue-limit equivalent to that of a smooth specimen. Therefore, a semicircular slit with a depth of 0.2 mm can be rendered harmless by LP in terms of the fatigue limit. The defect size of a 0.2 mm deep semicircular slit is greater than that of the largest defect induced by additive manufacturing (AM). Thus, the LP process can contribute to improving the reliability of additive-manufactured metals. Compressive residual stress is the dominant factor in improving fatigue strength and rendering surface defects harmless. Moreover, the trend of the defect size that can be rendered harmless, estimated based on fracture mechanics, is consistent with the experimental results.

Effects of Laser Peening Treatment on High Cycle Fatigue and Crack Propagation Behaviors in Austenitic Stainless Steel

2009 ◽  
Author(s):  
Yasuo Ochi ◽  
Kiyotaka Masaki ◽  
Takashi Matsumura ◽  
Takaaki Ikarashi ◽  
Yuji Sano
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Surface Layer ◽  
Fatigue Crack ◽  
Fatigue Strength ◽  
Crack Propagation ◽  
Compressive Residual Stress ◽  
High Cycle Fatigue ◽  
Laser Peening ◽  
Cycle Fatigue

Laser peening without protective coating (LPwC) treatment is one of surface enhancement techniques using impact wave of high pressure plasma induced by laser pulse irradiation. One of the effects of the LPwC treatment is expected to reduce the tensile residual stress and to induce the compressive residual stress in the surface layer of metallic materials. As a laser has no reaction force due to irradiation and also it has easy characteristics for remote control, the LPwC treatment is practically used as a technique for preventing the stress corrosion cracking (SCC) and for improving the fatigue strength of some structural materials. In this study, high cycle fatigue tests with four-points rotating bending loading were carried out on the non-peened and the LPwC treated low-carbon type austenitic stainless steel 316L in order to investigate the effects of the LPwC treatment on the high cycle fatigue strength and the surface fatigue crack propagation behavior. Two types of specimens were prepared; one was a smooth specimen, the other was a specimen with a pre-crack by the fatigue loading from a small artificial hole. As the results of the LPwC treatment, the high compressive residual stress was induced in the surface layer on the specimens, and the region of the compressive residual stress was about 1mm depth from the surface. The fatigue strength of the LPwC treated SUS316L was remarkably improved during the whole regime of the fatigue life up to the 108 cycles compared with the non-peened materials. Through the fracture mechanics investigation of the pre-cracked materials after the LPwC treatment, it became clear that the fatigue crack propagation was restrained by the LPwC treatment on the pre-cracked region, when the stress intensity factor range ΔK on the crack tip was under the value of 7.6 MPa√m.

Effect of Pre-Strain and Roller Working on Torsional Fatigue Properties of a Structural Steel

2011 ◽  
Vol 295-297 ◽  
pp. 2227-2230
Author(s):  
Cong Ling Zhou
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Work Hardening ◽  
Compressive Residual Stress ◽  
Strain Ratio ◽  
Fatigue Tests ◽  
The Other ◽  
Fatigue Properties ◽  
Torsional Fatigue ◽  
Stress Work

In this study, fatigue tests have been performed using two kinds of specimens made of 25 steel. One is pre-strained specimen with pre-strain ratio changing from 2% to 8% by tension, the other is roller worked with deformation of 0.5 mm and 1.0 mm in diameter direction. In the case of pre-strained specimen, the fatigue limit increases according to increase of tensile pre-strain, the fatigue limit of 8% pre-strained specimen is 25% higher than that of non-pre-strained one; in the case of roller worked specimen, the fatigue limit of R05 and R10 is 126% and 143% to that of non-roller worked specimen, respectively. These remarkable improvements of fatigue limit would be caused by the existence of compressive residual stress, work-hardening and the elongated microscopic structures.

312 Impartment of compressive residual stress on materials surface by laser peening

2006 ◽  
Vol 2006.14 (0) ◽  
pp. 167-168
Author(s):  
Yuji SANO ◽  
Koichi AKITA ◽  
Kiyotaka MASAKI ◽  
Yasuo OCHI
Keyword(s):  
Residual Stress ◽  
Compressive Residual Stress ◽  
Laser Peening

scholarly journals Enhancement of Fatigue Strength on SAE 1541 Steel Link Plate with Slip Ball Burnishing Technique

2020 ◽  
Vol 70 (4) ◽  
pp. 454-460
Author(s):  
K. Krishnakumar ◽  
A. Arockia Selvakumar
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Strength ◽  
Compressive Residual Stress ◽  
Repeated Loading ◽  
Ball Burnishing ◽  
Novel Technique ◽  
Conventional Process ◽  
Chain Link ◽  
Local Plastic Deformation

This research paper describes a technique for the enhancement of the fatigue strength of the chain link plate in the drive system of a military armoured vehicle. SAE 1541 steel link plates of chains were subjected to cyclical tensile stress due to repeated loading and un-loading conditions. The crack was getting originated from the pitch hole and growth perpendicular to the chain pulling load, due to fatigue mechanism. In general plate holes are manufactured using the conventional process. An additional novel technique called the slip ball burnishing (SBB) method is applied for improving the hole properties. The improvement is made by producing local plastic deformation, improving surface finish and compressive residual stress throughout in the pierced hole. Both the conventional process (CP) and the SBB technique have been evaluated by optical, profile, surface roughness and micro harness tests. Experimental fatigue test validations were done in both chain samples using the Johnson-Goodman method. SBB chains passed 3x106 cycles at the load of 17.61 kN and CP chains passed 3x106 cycles at the load of 13.92 kN. The conclusion was that SBB made a significant improvement of 26.51 per cent of fatigue strength compared to CP.

GS0211-270 Fatigue Strength of High Tensile Steel Spot-weld : 3. Improvement by Compressive Residual Stress

2015 ◽  
Vol 2015 (0) ◽  
pp. _GS0211-27-_GS0211-27
Author(s):  
Takanori NAKAGAKI ◽  
Shoji HOTTA ◽  
Tomohiro SUZUKI ◽  
Tatsuyuki AMAGO ◽  
Atsushi FUJII ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Compressive Residual Stress ◽  
Spot Weld

Dynamic Analysis of Residual Stress Introduced by Laser Peening

2006 ◽  
Vol 524-525 ◽  
pp. 135-140 ◽  
Author(s):  
Koichi Akita ◽  
Masatoshi Kuroda ◽  
Philip J. Withers
Keyword(s):  
Residual Stress ◽  
Compressive Residual Stress ◽  
Pressure Pulse ◽  
Peak Pressure ◽  
Single Pulse ◽  
Laser Peening ◽  
Threshold Pressure ◽  
Focusing Effect ◽  
Dynamic Finite Element ◽  
Long Pulse

Residual stress induced by laser single pulse irradiation was analyzed using a dynamic finite element code, ABAQUS/Explicit. The effects of the magnitude and length of a surface pressure pulse having a circular top-hat shape on the final residual stress in Ti-6Al-4V were investigated. A high peak pressure and/or a long pulse duration was effective in generating large compressive residual stress deep beneath the surface. However, large tensile residual stress features occurred near the centre and edge of the laser spot on the surface for high pressure and/or long pulse durations due to a radial focusing effect. Use of shorter pulse durations avoided this. The peak pressure (3GPa) required to induce a surface compressive residual stress across the whole area of the spot was slightly higher than the threshold pressure needed to plastically deform the surface.

Evaluating the fatigue limit of metals having surface compressive residual stress and exhibiting shakedown

2019 ◽  
Vol 43 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Jinta Arakawa ◽  
Tatsuya Hanaki ◽  
Yoshiichirou Hayashi ◽  
Hiroyuki Akebono ◽  
Atsushi Sugeta
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Compressive Residual Stress

Optimization of Laser Peening Parameters Using Taguchi Method

2007 ◽  
Vol 10-12 ◽  
pp. 692-696 ◽  
Author(s):  
Yue Qing Sun ◽  
Jian Zhong Zhou ◽  
Yi Bin Chen ◽  
Shu Huang
Keyword(s):  
Residual Stress ◽  
Taguchi Method ◽  
Compressive Stress ◽  
Compressive Residual Stress ◽  
Residual Compressive Stress ◽  
Critical Parameters ◽  
Laser Peening ◽  
The Finite Element Method ◽  
Optimal Setting ◽  
The Impact

Using Taguchi method to optimize the critical parameters of laser peening (LP) is presented firstly. The objective of the study is to assess the impact of laser parameters on the laser peen strengthening for the 6061-T6 aluminum alloy and optimize the process parameters to achieve higher surface residual compressive stress. In order to reduce the process cost and time, the finite element method was applied to simulate the LP process. The Taguchi method is used to formulate the experimental layout and establish the order of predominance among the identified critical parameters, and predict the optimal setting for each process parameter. The results show that three parameters related to the magnitude of compressive residual stress imply different effects. Laser shot diameter ranks first, followed by pulse width and laser power in terms of their effects on the magnitude of compressive residual stress. The best combination of levels is given by the levels (3, 3, 2). The optimal result was confirmed with a superior ultimate surface residual compressive stress of 125MP.

Influence of Microshot Peening on Surface Layer Characteristics of Cold Tool Steel

2007 ◽  
Vol 561-565 ◽  
pp. 897-900 ◽  
Author(s):  
Yasunori Harada ◽  
Kenzo Fukaura ◽  
Toshinori Aoki ◽  
Daien Yokoi ◽  
Yasushi Haruna
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Surface Layer ◽  
Fatigue Strength ◽  
Tool Steel ◽  
Compressive Residual Stress ◽  
Heating Furnace ◽  
Cemented Carbide ◽  
Compressed Air ◽  
New Type

Shot peening is a surface treatment and improves the performance of engineering components. More recently, a new type of microshot has been developed to enhance peening effect. In the present study, the influence of microshot peening on the surface layer characteristics of cold tool steel was investigated. In the experiment, the microshot peening apparatus with a heating furnace was produced experimentally. The projective method of the microshot was a compressed air type. The peening microshots of 0.1mm diameter were cemented carbide and the workpiece was commercially cold tool steel SKD11. Surface roughness, compressive residual stress, and hardness in the peened workpiece were measured. The effect of microshot peening on the fatigue strength of cold tool steel was also examined. The use of hard microshot such as cemented carbide was found to cause a significantly enhanced peening effect for cold tool steel.

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